1. Field of the Invention
The present invention relates in general to a flat panel display (FPD). In particular, the present invention relates to a liquid crystal display (LCD) with a non-matrix light shielding structure.
2. Description of the Related Art
Liquid crystal displays (LCDs) are a well-known form of flat panel display with advantages of low power consumption, light weight, thin profile, and low driving voltage. Generally, in LCDs, a liquid crystal layer is disposed between two transparent substrates such as glass substrates, and one of the two transparent substrates is provided with switching devices, such as thin film transistors (TFTs). In the display area of the LCD, an array of pixel areas is defined by horizontally extended scan lines and vertically extended signal lines. Each pixel area has a thin film transistor and a pixel electrode.
FIG. 19 is a cross section showing a conventional thin film transistor liquid crystal display (TFT LCD). In the lower substrate, an etch stopper inverse staggered type thin film transistor 15 is disposed on a portion of a lower glass substrate 1 and a pixel electrode 8 made of ITO is disposed on the other portion of the lower glass substrate 1. A passivation layer 9 for protecting the TFT 15 is arranged on the TFT 15. The TFT 15 has a gate 2a, a source 7a and a drain 7b. An insulating layer 3 is disposed between the pixel electrode 8 and storage electrode 2b to a form a capacitor 17. Numeral 4 indicates an active region, numeral 5 indicates an etch stopper and numeral 6 indicates an ohmic resistance contact layer.
In the upper substrate, a black matrix 12 is disposed on a portion of the upper glass substrate 11. The color filter layer 13 of red, green, and blue is disposed on another portion of the upper substrate corresponding to the pixel electrode. A common electrode 14 made of ITO is arranged on the black matrix 12 and the color filter 13.
U.S. Pat. Nos. 5,561,440 and 6,064,358 issued to Masaaki et al. on Oct. 1, 1996 and May 16, 2000 respectively, teaches that the light shielding structure disposed on the upper glass substrate has openings arranged in a matrix and is aligned with the TFT array on the lower glass substrate with each pixel electrode aligned with the opening in the light shielding structure and the edges of each pixel electrode are overlapped by the periphery of the light shielding structure. U.S. Pat. No. 6,424,394 issued to Morii on Jul. 23, 2002 teaches that the shape of the light shielding film is grid-shaped so as to transmit the light. As shown in FIG. 20, the black matrix 12, i.e., a light shielding portion in a grid-shaped pattern is shown with hatching, and the aperture portion 18, i.e., a light transparent portion is shown with white painting. The black matrix 12 shapes the periphery of the display portion of each color picture element of the primary colors R, G and B, adjacent to each other of a color filter 13 to prevent bleeding of each color, such that color mixture is thereby prevented. The black matrix 12 is commonly used to improve the contrast of the color display and to increase the display quality.
However, the black matrix 12 consisting of Cr on the upper substrate is subject to great stress due to the thermal expansion coefficient difference between the black matrix and the glass substrate and between the black matrix and the color filter when forming the upper substrate. The R, G, and B color filter may peel due to the stress induced by the thermal cycles required to manufacture the upper substrate and to be released from the black matrix.